a. Field of the Invention
This invention relates to dihydroxyphenylpyridines, intermediate dimethoxyphenylpyridines, their preparation and their use as cardiotonics.
b. Description of the Prior Art
4-(3,4-Dimethoxyphenyl)pyridine, inter alia, is shown in A. C. Ritchie U.S. Pat. No. 3,575,985, issued Apr. 20, 1971, as an intermediate in the preparation of 4-(3,4-dimethoxyphenyl)-1-methylpyridinium iodide, which was heated with aqueous hydrogen bromide in acetic acid to form a mixture of 4-(3,4-dihydroxyphenyl)-1-methylpyridinium iodide and bromide. The iodide-bromide mixture was treated with freshly prepared silver chloride to produce 4-(3,4-dihydroxyphenyl)-1-methylpyridinium chloride. The pyridinium salts of U.S. Pat. No. 3,575,985 were said to have "an effect upon the cardiovascular and nervous systems for example possessing antihypertensive activity and able to block or stimulate antonomic ganglia".
4-(3-Hydroxyphenyl)pyridine is shown, inter alia, by Coates et al. [J. Chem. Soc. 1943, 406].
Ginos et al. [J. Med. Chem. 18, 1194 (1975)] show, as an intermediate, 2-(3,4-dihydroxybenzyl)pyridine.